Test device for buck circuit

ABSTRACT

A test device includes a transformer, a loop analyzer, and a protection circuit. The protection circuit includes a control unit, a signal acquisition and amplification unit, and an electronic switch. When the loop analyzer outputs a signal, the signal acquisition and amplification unit acquires the signal output from the loop analyzer, amplifies the acquired signal, and outputs the amplified signal to the control unit. The control unit transforms the received signal from analog form to digital form, and compares the digital signal with a reference value. If the digital signal is greater than the reference value, the control unit outputs a control signal to the electronic switch, to turn off the electronic switch. The signal output from the loop analyzer cannot be transmitted to a buck circuit.

BACKGROUND

1. Technical Field

The present disclosure relates to a test device.

2. Description of Related Art

During testing of a buck circuit, a reference value of a radio frequency(RF) signal output to the buck circuit is usually set in a loop analyzerbefore the test. However, when a fact setting value that is greater thanthe reference value is input by mistake, it will cause damage to thebuck circuit.

BRIEF DESCRIPTION OF THE DRAWING

Many aspects of the present disclosure can be better understood withreference to the following drawing(s). The components in the drawing(s)are not necessarily drawn to scale, the emphasis instead being placedupon clearly illustrating the principles of the present disclosure.Moreover, in the drawing(s), like reference numerals designatecorresponding parts throughout the several views.

The FIGURE is a block diagram of an embodiment of a test deviceconnected to a buck circuit.

DETAILED DESCRIPTION

The FIGURE is a block diagram of an embodiment of a test device 100connected to a buck circuit 10. The test device 100 includes atransformer 20, a loop analyzer 30, and a protection circuit 50. Thetest device 100 is used for testing the buck circuit 10.

The buck circuit 10 includes a first terminal 12 and a second terminal16. The transformer 20 includes a primary coil 22 and a secondary coil26. The loop analyzer 30 includes first to fourth signal terminals31-34. The protection circuit 50 includes a control unit 52, a signalacquisition and amplification unit 56, a display unit 58, and anelectronic switch Q.

The first signal terminal 31 of the loop analyzer 30 is grounded, andconnected to a first end of the primary coil 22. The second signalterminal 32 of the loop analyzer 30 is connected to a second end of theprimary coil 22, and connected to the signal acquisition andamplification unit 56, and outputs a radio frequency (RF) signal to thesignal acquisition and amplification unit 56. The third signal terminal33 of the loop analyzer 30 is connected to the first terminal 12 of thebuck circuit 10. The fourth signal terminal 34 of the loop analyzer 30is connected to the second terminal 16 of the buck circuit 10.

A first end of the secondary coil 26 is connected to the first terminal12 of the buck circuit 10. A second end of the secondary coil 26 isconnected to a first end of the electronic switch Q. A second end of theelectronic switch Q is connected to the second terminal 16 of the buckcircuit 10. A third end of the electronic switch Q is connected to thecontrol unit 52.

In the embodiment, the transformer 20 is an isolation transformer.Number of windings of the primary coil 22 is the same as number ofwindings of the secondary coil 26. The control unit 52 can be a singlechip computer, in one example. The display unit 58 can be a liquidcrystal display (LCD), in one example.

In the embodiment, the electronic switch Q is an n-channel metal oxidesemiconductor field-effect transistor (MOSFET), and the first to thirdends of the electronic switch Q correspond to a source, a drain, and agate of the MOSFET, respectively.

In use, the value of the RF signal output from the second signalterminal 32 of the loop analyzer 30 is set in the loop analyzer 30. Thesignal acquisition and amplification unit 56 receives the RF signaloutput from the second signal terminal 32, amplifies the RF signal, andoutputs the amplified RF signal to the control unit 52. The control unit52 transforms the RF signal from analog to digital to get a digitalsignal, and compares the digital signal with a reference value. Thedisplay unit 58 is controlled by the control unit 52 to display thedigital signal and the reference value.

If the value of the digital signal is greater than the reference value,the control unit 52 outputs a low level voltage signal, such as logic 0.The electronic switch Q is turned off. The first end of the electronicswitch Q is disconnected from the second end of the electronic switch Q.The RF signal output from the second signal terminal 32 cannot betransmitted to the buck circuit 10 through the transformer 20.Therefore, the buck circuit 10 is prevented from being damaged.

If the value of the digital signal is less than the reference value, thecontrol unit 52 outputs a high level voltage signal, such as logic 1.The electronic switch Q is turned on. The first end of the electronicswitch Q is connected to the second end of the electronic switch Q. TheRF signal output from the second signal terminal 32 is transmitted tothe buck circuit 10 through the transformer 20. The RF signal istransmitted from the second terminal 16 to the first terminal 12 of thebuck circuit 10. The third signal terminal 33 receives the RF signalfrom the first terminal 12 of the buck circuit 10. The fourth signalterminal 34 receives the RF signal from the second terminal 16 of thebuck circuit 10. Therefore, the loop analyzer 30 determines whether theRF signal received from the buck circuit 10 is same with the RF signalset in the loop analyzer 30, thereby testing the stability of the buckcircuit 10.

While the disclosure has been described by way of example and in termsof preferred embodiment, it is to be understood that the disclosure isnot limited thereto. To the contrary, it is intended to cover variousmodifications and similar arrangements as would be apparent to thoseskilled in the art. Therefore, the range of the appended claims shouldbe accorded the broadest interpretation so as to encompass all suchmodifications and similar arrangements.

What is claimed is:
 1. A test device for testing a buck circuit, thetest device comprising: a transformer comprising a primary coil and asecondary coil, wherein a first end of the secondary coil is connectedto a first terminal of the buck circuit; a protection circuit comprisinga control unit, a signal acquisition and amplification unit, and anelectronic switch, wherein a first end of the electronic switch isconnected to a second end of the secondary coil, a second end of theelectronic switch is connected to a second terminal of the buck circuit,the third end of the electronic switch is connected to the control unit,the control unit is connected to the signal acquisition andamplification unit; and a loop analyzer comprising first to fourthsignal terminals, wherein the first signal terminal of the loop analyzeris connected to a first end of the primary coil, the second signalterminal of the loop analyzer is connected to a second end of theprimary coil and the signal acquisition and amplification unit, thethird signal terminal is connected to the first terminal of the buckcircuit, the fourth signal terminal is connected to the second terminalof the buck circuit; wherein when the second signal terminal of the loopanalyzer outputs a signal to the signal acquisition and amplificationunit, the signal acquisition and amplification unit amplifies the signaloutputted from the loop analyzer, and outputs an amplified signal to thecontrol unit; the control unit transforms the amplified signal fromanalog form to digital form to get a digital signal, and compares thedigital signal with a reference value; if the value of the digitalsignal is greater than the reference value, the control unit outputs afirst control signal to the electronic switch, to turn off theelectronic switch; if the value of the digital signal is less than thereference value, the control unit outputs a second control signal to theelectronic switch, to turn on the electronic switch; the loop analyzerdetermines whether the signal received from the buck circuit is samewith the signal set in the loop analyzer.
 2. The test device of claim 1,wherein the protection circuit further comprises a display unitconnected to the control unit, and the display unit is controlled by thecontrol unit to display the digital signal and the reference value. 3.The test device of claim 2, wherein the display unit is a liquid crystaldisplay (LCD).
 4. The test device of claim 1, wherein the control unitis a single chip computer.
 5. The test device of claim 1, wherein thetransformer is an isolation transformer, a number of windings of theprimary coil is the same as a number of windings of the secondary coil.6. The test device of claim 1, wherein the electronic switch is a metaloxide semiconductor field-effect transistor (MOSFET), the first to thirdends of the electronic switch correspond to a source, a drain, and agate of the MOSFET, respectively.
 7. The test device of claim 1, whereinthe signal outputted from the second signal terminal of the loopanalyzer is a radio frequency signal.